U.S. patent number 8,189,325 [Application Number 12/330,941] was granted by the patent office on 2012-05-29 for switchgear.
This patent grant is currently assigned to Hitachi, Ltd.. Invention is credited to Takumi Ishikawa, Takuya Kurogi, Naoki Nakatsugawa, Kenji Tsuchiya, Nobuyuki Yamada.
United States Patent |
8,189,325 |
Kurogi , et al. |
May 29, 2012 |
Switchgear
Abstract
A switchgear case is partitioned into a high voltage bus bar
chamber, which contains bus bars and cable heads, a high voltage
device chamber containing circuit breakers and operation mechanisms
and a low voltage control chamber containing a relay and
measurement devices, etc. A rear wall of the case has a first
suction port disposed at a lower part thereof, wherein the high
voltage bus bar chamber, high voltage device chamber and the low
voltage control chamber are communicated and air passing through
the chambers is discharged from a first discharging port of the
casing. The bus bars electrically connecting the high voltage
devices in the high voltage device chamber and connecting bars
connecting the adjoining bus bars and the cable heads are covered
with solid insulators for solid-insulation.
Inventors: |
Kurogi; Takuya (Hitachi,
JP), Tsuchiya; Kenji (Hitachi, JP),
Nakatsugawa; Naoki (Hitachinaka, JP), Ishikawa;
Takumi (Hitachi, JP), Yamada; Nobuyuki (Tokyo,
JP) |
Assignee: |
Hitachi, Ltd. (Tokyo,
JP)
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Family
ID: |
40382278 |
Appl.
No.: |
12/330,941 |
Filed: |
December 9, 2008 |
Prior Publication Data
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Document
Identifier |
Publication Date |
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US 20090159569 A1 |
Jun 25, 2009 |
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Foreign Application Priority Data
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Dec 18, 2007 [JP] |
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2007-325716 |
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Current U.S.
Class: |
361/678;
218/157 |
Current CPC
Class: |
H02B
13/01 (20130101); H02B 1/56 (20130101) |
Current International
Class: |
H05K
7/20 (20060101) |
Field of
Search: |
;218/157
;361/379,678 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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P2000-139006 |
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May 2000 |
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CN |
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2615008 |
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May 2004 |
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CN |
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2652000 |
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Oct 2004 |
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CN |
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1 343 233 |
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Sep 2003 |
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EP |
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4-124811 |
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Nov 1992 |
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JP |
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08-019125 |
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Jan 1996 |
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JP |
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9-93730 |
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Apr 1997 |
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JP |
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2000-139006 |
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May 2000 |
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JP |
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2000-228803 |
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Aug 2000 |
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JP |
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2007-020295 |
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Jan 2007 |
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JP |
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Other References
Authorized Officer: Jozsef Schwarczkopf, Written Opinion and Search
Report received in Singapore Patent Application No. 200809093-8,
Oct. 13, 2011, 13 pp., Hungarian Intellectual Property Office.
cited by other .
Taiwanese Office Action received in Taiwan Patent Application No.
097143336, mailed: Jan. 2, 2012, 7 pp., Taiwan Patent Office,
Taiwan. cited by other.
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Primary Examiner: Nguyen; Truc
Attorney, Agent or Firm: Mattingly & Malur, P.C.
Claims
What is claimed is:
1. A switchgear comprising: a casing partitioned into at least four
chambers comprising a high voltage bus bar chamber, which contains
at least bus bars and cable heads, a high voltage device chamber
containing at least circuit breakers and a low voltage control
chamber containing at least a relay and measurement devices,
wherein the casing is constituted by a rear wall, a front wall
opposed to the rear wall, a bottom wall, a top wall opposed to the
bottom wall, and side walls each connected to the top wall, bottom
wall, front wall and rear wall, the rear wall having a first
suction port disposed at a lower part thereof, wherein the high
voltage bus bar chamber, the high voltage device chamber and the
low voltage control chamber are communicated and air passing
through the chambers is discharged from a first discharging port of
the casing, the first suction port being provided with a first
filter, a second suction port provided with a third filter being
disposed between the high voltage bus bar chamber and the low
voltage control chamber, wherein bus bars electrically connecting
the high voltage devices in the high voltage device chamber and
connecting bars connecting the adjoining bus bars and the cable
heads are covered and insulated with solid insulators, and wherein
the second suction port has a smaller cross sectional area than the
first suction port, and the third filter has a smaller pore size
than the first filter.
2. The switchgear according to claim 1, wherein the bus bars are
insulated with hard thermoset resin and the connecting bars are
insulated with a flexible resin.
3. The switchgear according to claim 2, wherein the hard thermoset
resin is an epoxy resin and the flexible resin is a silicone
rubber.
4. The switchgear according to claim 1, wherein the surfaces of the
solid insulators are covered with an earthing film to earth the
solid insulators.
5. The switchgear according to claim 1, wherein the high voltage
device chamber contains at least two circuit breakers, each of
which is contained in a container isolated from the high voltage
bus bar chamber and the low voltage control chamber, each of the
containers having a fine filter disposed between the high voltage
bus bar chamber and high voltage device chamber, the fine filters
allowing only very small dust particles or only air to pass
therethrough.
6. The switchgear according to claim 1, wherein the first
discharging port is provided with a second filter and is disposed
in the top wall.
7. The switchgear according to claim 1, wherein a second discharge
port and a fourth filter are disposed above the high voltage device
chamber.
8. The switchgear according to claim 1, wherein the pore size of
the first filter is larger than that of the second, third, fourth
and fine filters, and the pore size of the third filter is smaller
than that of first filter.
9. The switchgear according to claim 1, wherein the pore size of
the fourth filter is smaller than that of the third filter.
Description
CLAIM OF PRIORITY
The present application claims priority from Japanese patent
application serial No. 2007-325716, filed on Dec. 18, 2007, the
content of which is hereby incorporated by reference into this
application.
THE FIELD OF THE INVENTION
The present invention relates to a switchgear with improved dust
prevention performance and maintenance saving.
RELATED ART
Switchgears generally comprises a casing enclosing a high voltage
cable chamber containing at least bus-bars and cable heads, a high
voltage device chamber containing at least two circuit breakers,
and a low voltage control chamber containing at least measurement
instruments and relays. The three chambers are substantially
independent from each other, while the air for cooling the devices,
etc. in the chambers is communicated and circulated towards an air
discharging port. In the above switchgear there are various air
circulation systems so as to keep clean the inside of the casing
and to suppress temperature rise inside. For example, Japanese
patent laid-open 2000-228803, Japanese patent laid-open H08-19125,
Japanese patent laid-open 2000-139006, Japanese patent laid-open
2007-20295, etc disclose different switchgears having cooling
systems. By forming the air circulation in the casing, the dust in
the casing is blow out from the casing and temperature in the
casing is lowered simultaneously. In the prior art such as Japanese
patent laid-open H08-19125 a filter is formed at the bottom wall of
the casing on which a transformer is placed. However, this
structure is not effective to circulate air in the casing. The
suction port may become an obstacle to the airflow. Japanese patent
laid-open 2000-228803 has the same problem.
In Japanese patent laid-open 2000-139006 the high voltage devices
such as circuit breakers are placed in the airflow. However, the
airflow that communicates with the suction port contains dust, etc
and the high voltage devices may be easily soiled with the dust,
etc.
In Japanese patent laid-open H08-19125 cables, bus bars and cable
heads are exposed to the airflow. Therefore, the cables, bus bars
or cable heads may be soiled with dust, etc in the airflow. This
means the cables or cable heads should be frequently maintained or
cleaned. This problem may arise from the technology disclosed in
Japanese patent laid-open 2000-228803.
In Japanese patent laid-open 2007-20295 a plurality of fans are
used to pressure the inside of the casing and circulate air in the
casing. This structure, of course, makes large the switchgear size
and increases a cost of the switchgear.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a switchgear
that has improved dust prevention performance and maintenance
saving, while keeping good heat dissipating performance.
The present invention provides a switchgear comprising: a casing
partitioned into at least four chambers comprising a high voltage
bus bar chamber, which contains at least bus bars and cable heads,
a high voltage device chamber containing at least circuit breakers
and a low voltage control chamber containing at least a relay and
measurement devices, wherein the casing for three chambers is
constituted by a rear wall, a front wall opposed to the rear wall,
a bottom wall, a top wall opposed to the bottom wall, and side
walls each connected to the top wall, bottom wall, front wall and
rear wall, the rear wall having a first suction port disposed at a
lower part thereof, wherein the high voltage bus bar chamber, high
voltage device chamber and the low voltage control chamber are
communicated with air and air passing through the chambers is
discharged from a first discharging port of the casing,
wherein bus bars electrically connecting the high voltage devices
in the high voltage device chamber and connecting conductors 25
connected to connecting bars 7' to connect the adjoining bus bars
are covered with solid insulators for solid-insulation.
The bus bars 7 are insulated with hard thermoset resin and the
connecting bars 7' are insulated with a flexible resin. The hard
thermoset resin may preferably be an epoxy resin and the flexible
resin may preferably be a silicone rubber. The high voltage device
chamber contains at least two circuit breakers, such as vacuum
circuit breakers, each of which is contained in a container or a
closing cover 3 isolated from the high voltage bus bar chamber and
the low voltage control chamber, each of the containers having a
fine filter disposed between the high voltage cable chamber and
high voltage device chamber, the fine filters allow only very small
dust particles or only gaseous substances such as air or steam to
pass therethrough.
The high voltage bus bar chamber, the high voltage device chamber
and the low voltage control chamber are communicated with air by
means of fine filters 14, 16 to a second filter disposed to the top
wall 1B or the like. The first suction port 9 and the first filter
10 are disposed at a lower part of the rear wall, a second suction
port 11 and third filter 12 are disposed in the partition wall 1F
between the high voltage bus bar chamber 2 and the high voltage
device chamber 4, and a first exhaust port or discharging port 17
and second filter 20 are disposed in the top wall 1B or the
like.
A second discharge port 18 and a fourth filter 22 are disposed
above the low voltage control chamber 5. The pore size of the first
filter 10 is larger than that of the second filter 20, and the pore
size of the third filter 12 is smaller than that of the first
filter 10.
The pore size of the fourth filter 22 is smaller than that of the
third filter 12. The fifth and sixth filters allow only very small
dust particles or gaseous substance such as air, steam, etc, to
pass therethrough. The second filter 20 and fourth filter 22 may be
omitted.
According to the present invention, the cables, connecting bars or
bus bars and cable heads in the high voltage bus bar chamber are
firmly insulated and protected from dust, moisture, salts, etc in
the airflow. And, devices in the high voltage device chamber, such
as circuit breakers are isolated substantially completely from
dust, moisture, salts, etc. The airflow in the casing is formed by
natural circulation by the action of upward airflow caused by heat
generated in the heat generating components in the casing from the
lower part of the casing toward the top portion of the casing, the
dust, etc is easily flown out and heat is dissipated to outside the
casing. Therefore, reliability of the switchgear of the present
invention will be remarkably improved. As a result, the switchgear
of the present invention is featured by low-cost, anti-dust
structure and remarkable maintenance saving.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a cross-sectional side view of a unit switchgear of the
present invention.
FIG. 2 is a perspective view of the unit switchgear shown in FIG.
1.
FIG. 3 is a rear side view of the unit switchgear shown in FIGS. 1
and 2 of the present invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
First of all, some of the features of the switchgear of the present
invention will be listed and explained below. The switchgear of the
present invention should have one or more features.
The switchgear of the present invention comprises:
(1) A casing partitioned into at least three chambers, i.e. a high
voltage bus bar chamber, which contains at least bus bars and cable
heads, a high voltage device chamber containing at least circuit
breakers and a low voltage control chamber containing at least a
relay and measurement devices. The casing should cover and protect
the necessary components of the switchgear from environment.
(2) The casing is constituted by a rear wall, a front wall opposed
to the rear wall, a bottom wall, and a top wall opposed to the
bottom wall, the rear wall having a first suction port disposed at
a lower part thereof, the top wall having an exhaust port disposed
above the high voltage bus bar chamber or in the top wall, wherein
the high voltage bus bar chamber and the high voltage device
chamber are partitioned.
(3) The lower part of the high voltage device chamber and the low
voltage control chamber are air-communicated by means of a second
suction port and a filter, and the high voltage device chamber is
divided into at least two device sections each of which
accommodates a circuit breaker.
(4) The device containers or closing cover 3 for the high voltage
devices are independent from each other and each of the device
containers or closing covers is communicated with the high voltage
bus bar chamber by means of fine filters 14, 16.
(5) The bus bars and cable heads in the high voltage cable chamber
are covered with solid insulators. The bus bars and the cable heads
are insulated with epoxy resin, and the connecting bars connected
to connecting conductors for connecting the adjoining bus bars are
insulated with flexible silicone rubber. Since the connecting bars
are moved when the unit switchgears are disconnected or replaced,
the solid insulator should be flexible. The first suction port 9
allows relatively large sized dust, etc to flow into the high
voltage bus bar chamber. The air containing dust flows upwards by
the action of a rising airflow in the bus bar chamber, etc. The
cable heads and bus bars are not soiled at all by the dust because
they are completely covered with solid insulators.
(6) The containers for the circuit breakers are independent from
each other and from the high voltage bus bar chamber and low
voltage control chamber. However, each of the containers or closing
covers communicates with the high voltage bus bar chamber by means
of fine filters 14, 16 disposed in the suction-discharge ports 13,
15. Since the fine filters have a very small pore size, they allow
only very small dust particles or salts or only gaseous substances
such as air, steam to path therethrough. Accordingly, the inside of
the containers is kept clean all the time.
(7) The preferable relationships of pore sizes among the filters
10, 12, 14, 16, 20, 22 are as follows.
The pore size of the first filter 10 is the largest in the filters.
The first filter 10 functions to remove relatively large dust
particles. The pore size of the second filter 20, if used, may be
the same of that of the first filter 10 or smaller than that of the
first filter 10.
The pore size of the third filter 12 is smaller than that of the
first filter 10 and, preferably than that of second filter 20, if
used. The pore size of the fourth filter 22 is preferably smaller
than that of the second filter 20 or the third filter, but may be
the same as that of the third filter 12.
In the following the embodiment of the present invention will be
explained. FIGS. 1 to 3 show the embodiment of the switchgear of
the present invention. In these figures a main body or a casing 1
of the switchgear is constituted by a bottom wall 1A, a top wall
1B, and side walls 1C between the top wall and the bottom wall. The
casing has a front door 1D and a rear door 1E. The doors are used
when the switchgear is inspected or repaired or subjected to
replacement of components.
The casing comprises a high voltage bus bar chamber 2, which is
constituted by the bottom wall 1A, the top wall 1B and a partition
wall 1F. The high voltage bus bar chamber is generally positioned
at the backward side of the casing 1. The two high voltage device
chambers 4 are formed between the high voltage bus bar chamber 2
and a low voltage control chamber 5 by a containers or closing
covers 3. The container 3 of the device chamber includes circuit
breakers 6, which are structurally isolated from airflow in the
casing 1 by doors 24 and partitions 23. The container 3 also
includes an operation mechanism (Not shown) connected to movable
electrodes of the circuit breakers. This does not mean that the
containers for the vacuum circuit breakers 6 are air-tightly
isolated from the low voltage control chamber 5 and from the high
voltage bus bar chamber 2. The partitions 23 are disposed to
prevent from inserting of hands or finger of an operator at the
time of maintenance or other jobs. The casing 1 has the front door
1D to open the switchgear at the time of maintenance or other jobs.
The circuit breakers 6 are withdrawing type, and they can be
withdrawn from the main body with handles disposed on the door 24
of the container.
The high voltage bus bar chamber 2 confines high voltage bus bars
7, which are covered with a solid insulator such as epoxy resin.
The connecting bars 7' are covered with a flexible solid insulator
such as silicone rubber. Since the connecting bars 7' may be moved
when one or more of the bus bars are replaced or connected to
connecting conductors, the connecting bars 7' should be flexible.
The bars 7' stand up from the connecting portions of the
solid-insulated conductors 7, as shown in FIG. 2. In general, the
vacuum switchgear is used in combination of two or more unit
switchgears shown in FIGS. 1-3. Therefore, the solid insulated
conductors are connected to those of the adjoining switchgears.
Connecting rods 25 (dotted lines) are extending in a horizontal
direction to connect the solid-insulated bus bar 7 of the adjoining
switchgears.
The solid insulators of the bus bar 7 and connecting bar 7' are
covered with earth layers 26, 27.
The cable heads 8 connected to the fixed electrodes of the circuit
breakers are also covered with a solid insulator such as epoxy
resin. The components are electrically insulated from the
surrounding for protecting them from humidity, salts or dust.
Accordingly, the maintenance of the cable heads, connecting bars
and bus bars are very simplified and time saving. The air that
contains dust, etc naturally flows upwards and flows out from the
first discharging port 17 by the action of natural circulation by
heat generated in the bus bars, cable heads and connecting bars.
Since the bus bars, etc are solid insulated, large particle dust,
etc passed through the first filter does not damage them. In order
to accelerate suction of air as much as possible, the cross
sectional area of the first suction port and the pore size of the
first filter should be sufficiently large.
A part of the air flown from the first filter may go through the
third filter 12, which has a pore size smaller than that of the
first filter, into a lower part of the high voltage device chamber.
Since the high voltage devices such as vacuum circuit breakers 6
are covered in the closing cover 3, the dust contained in the
airflow does not damage or soil them. The containers for the vacuum
circuit breakers may breathe by means of the fine filters 14, 16
made of Gore-Tex (Registered trademark), a film for passing only
gaseous substances. The air containing small size dust flows
upwards along the low voltage control chamber towards the second
discharging port 18, while cooling the equipments such as relays,
timers, etc.
The pore size of the fourth filter 22, if used, is preferably the
same as that of third filter 12. According to the above-explained
structure, the cooling air flows via necessary loops to cool the
components. The components of high voltage are highly protected
from environment containing dust, salts and humidity; the
maintenance of the components is remarkably simplified or
timesaving. The heat generating components as well as other
components are effectively cooled down by the airflow, because an
amount of which can be made sufficiently large, keeping its
cleanness.
Circuit breakers 6 and their operation mechanisms (not shown) are
installed in high voltage device chambers 4. This embodiment shows
two circuit system, which shows two high voltage chambers 4 and two
circuit breakers 6. Cable heads 8 are connected to fixed electrodes
of the circuit breakers 6. Measurement instruments, relays, etc are
disposed on the rear side of the front door 1D that constitute the
low voltage control chamber 5.
Below the rear side door 1E disposed is a first filter 10 in the
first suction port 9 for taking outside air into the high voltage
bus bar chamber 2. The third filter 12 is disposed in the third
suction port 11 for taking the air into the low voltage control
chamber 5 below the partition wall 1F. The fifth filter 14 and
sixth filter 16 for discharging air heated by heat generated in the
high voltage device chambers 4 are disposed in the first
suction-discharge port 13 and second suction-discharge port 15,
respectively, formed in the partition wall 1F. The second filter 20
is disposed in the first discharge port 17 for discharging air
heated by heat generated in the high voltage bus bar chamber 2 in
the top wall 1B. The fourth filter 22 is disposed in the second
discharge port 18 for discharging air heated by heat generated in
the low voltage control chamber 5 above the top wall corresponding
to the high voltage device chamber 4. The second discharge port 18
is opened not in the front side, but in the rear direction of the
main body for protecting operators or inspectors. The first
discharge port 17 is also opened in the upper direction. The second
filter 20 and forth filter 22 can be omitted.
Since a large quantity of heat is generated from the
solid-insulated high voltage bus bars 7 and connecting buses 7' at
the time of current flow, an area of the suction port 9 in the rear
wall 1E is large so as to intake a large amount of air for cooling.
The first filter 10 has such a pore size or filter pore size that
relatively large dust particles such as 5 .mu.m or more can pass
through it. The first filter 10 should have an airflow resistance
as small as possible.
The heat generated in the high voltage device chamber is discharged
into the low voltage control chamber 5 and equipments in the low
voltage control chamber 5 are protected from the dust, etc. Since a
quantity of heat generated in the low voltage control chamber is
smaller than that in the heat generated in the main circuit, an
amount of air for cooling can be smaller than that of the air taken
into the high voltage bus bar chamber 2. Therefore, a sectional
area of the second suction port 11 can be made smaller than that of
the first suction port 9. The pore size of the third filter 12 can
be made smaller than that of the first filter 10, such as 1 .mu.m
or less.
In order to protect the high voltage devices in the high voltage
device chambers 4 from the dust, etc the fifth filter 14 and sixth
filter 16 may allow the dust particles of 0.1 .mu.m or less to
pass. The high voltage device chambers can breathe through the
filters 14, 16, but they do not allow the dust, etc to enter the
chambers so that the high voltage devices such as circuit breakers,
operation mechanisms, etc are highly protected from the dust. The
filter materials for the fine filters 14, 16 are filters that allow
only very fine dust particles or gaseous substance to pass through.
Gore-Tex is an example of the materials suitable for the fifth and
sixth filters.
* * * * *